JPS58152328A - Relay cotact protecting circuit for wiper intermittent switch - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an automatic wiper device in which, when the switch is turned off to stop the wiper operation, even if the relay switch is opened, an arc is generated at the contact point, and when the switch is switched, (a) This invention relates to a relay contact protection circuit for a wiper intermittent switch that prevents the contacts from being damaged due to the formation of a short circuit due to an arc between the power supply and the ground amount.

Conventionally, in this type of wiper device, especially when using a high-voltage power supply sound of about 24V, when the wiper stop switch is pressed to disconnect the control circuit "k3Pi" and automatically stop the wiper, the relay contact is switched to open -\. At times, arcing occurs and a short circuit is formed between the contacts, often resulting in complete damage to the contacts. For example, in Figure 1 (a)
) shows the principle configuration of wiper motor M1, wiper motor interlocking cam switch SW, and relay (RLl) contact. A switch (not shown) is turned on, a relay (not shown) is activated, and the relay contact shown in FIG. -\ and normally closed contact terminal N. The motor M rotates when the switch is switched from , but for example, a high voltage of 24V is used as a power source for wiper equipment +T, and the arm of the wiper motor interlocking cam switch SW1 -
If it is at contact a on the ground side (motor off), the relay contact is centered at C81n and is at contact N on arm Bm.

From N. When the arc is switched to the N side, as shown in FIG. 1(b). From N. An arc jumps (g), and a short-circuit current i flows between the power supply and ground, damaging the relay contacts.

That is, FIG. 2 shows a practical circuit of the conventional circuit shown in FIG. 1(b). The switch SW1 and relay contacts in FIG. 2 correspond to those in FIG. 1(b). In 1
When the Kawabeshi wiper switch SW is turned on (=2) and a bias is applied to the base of the transistor IIIr, the transistor Tr becomes conductive and the relay I:LL1 is energized, so that the relay contact changes from Nc to N. The wiper motor M□ starts rotating. Then, the switch SW1 connected to the motor shaft is switched from contact a to bl, that is, from off to on, so that the diode D□
A bias is applied to the base of the transistor Tr through the resistor tk, and the transistor 'fr1 becomes conductive, and the transistor 'I'r connected to the collector side of the transistor continues to be biased, so that Relay RL1 continues to be energized.It is a circuit in which the wiper is turned on and off by transistor T'l, resistors R1, R, and capacitor C1.

By the way, if for some reason the motor M is locked and the rotation of the motor M is prevented, you may try to turn the switch S fully on and off to make the motor M0 fully rotate. , even if it is working fine,
For example, turn on the washer switch 8W, f, activate the washer link operation, rotate the motor Msk, and at the same time fully charge the capacitor C3 via the third diode Ds', and then complete the time constant circuit consisting of the capacitor C, resistor R, and Rt6. Then release the relay KL.

is disconnected and its contact is N. When the switch SW8 is at the motor stop position, that is, at the contact a side at the timing when the voltage is +N, an arc is generated at the relay contact as shown in FIG. -No. 1 The relay contacts are completely damaged because the flow flows to the ground through the switches SW and i.

It is an object of the present invention to provide a complete circuit which prevents damage to relay contacts under such conditions.

Next, embodiments of the present invention will be described and explained with reference to the accompanying drawings.

FIG. 1(C) shows the principle of the circuit of the present invention. In the present invention, the relay contacts are centered around the common contact C8m.
. From N. The switching timing is such that the switch SW□ connected to the wiper motor M1 is always turned to the contact side.

Therefore, (g) the circuit from the power source to the ground is cut off, so there is no possibility of arcing between the relay contacts as in conventional circuits.

FIG. 3 shows a concrete embodiment of the relay contact protection circuit according to the present invention, in which the principle of FIG. 1(C) is fully realized. In the same figure, the points that are different from FIG.
4-f: the resistor R and the transistor Tr,
a transistor Tr controlled according to the operating state of the
Since the other circuit configuration is the same as the one shown in FIG. 2, the same reference numerals are given.

In the operation of the circuit of FIG. 3, the intermittent wiper switch 8
When W and 2 are turned on, the transistor Tr becomes conductive and the relay RL is energized, so the relay contact is centered at C8m'. +No. Therefore wiper motor M
At the same time as 8 rotates, the transistor Tr is turned on via the resistor R1sk.

Therefore, the relays connected in parallel to the collector sides of the transistors T, , are self-maintained.

As the wiper motor M4 rotates as described above, the switch SW0 changes from off (contact a) to on (contact b).
Since the base of the transistor p Tr4 is biased and the transistor Tr4 becomes conductive, the transistor Tr4 becomes conductive.

will be turned off.

Therefore, at this time, switch SW 5 is turned on and off to excite relay 'fLL1, and washer switch 8W is turned on and relay RL1't is turned on.
Even if an attempt is made to excite the transistor Tr, as long as the contact of the switch SW□ is on the off side (a 01ll ), the transistor Tr
, continues to be in the on state, and relay 1 (Ll is never turned off (de-energized)), so contact N.-
In this case, there is no switching of contacts between No and no arc occurs. In other words, the transistor l1lr is rendered non-conductive when the contact of the switch SW□ is always on the a side, so even if the relay ItL is temporarily turned on due to the on/off operation of SW, ( g) Relay contact N from power supply.

- There is no possibility that a short circuit between earth and ＼ will be formed through Nci.

4 shows a circuit configuration of another embodiment in which 1) NP type transistors are used, whereas FIG. 6 uses NPN type transistors as transistors Tr1 to Tr6.
The only difference in the polarity of the transistors is that the operation is well known to those skilled in the art, so a description thereof will be omitted.

As described above, in the relay contact protection circuit according to the present invention, the relay contact is always switched only when the cams (7) switch SW1, which is linked to the wiper motor, is connected to the on side. Damage to relay contacts due to arcing can be prevented.

[Brief explanation of the drawing]

Figure 1 (a) is a principle diagram explaining the entire operation of the wiper device, Figure 1 (b) is a principle diagram showing the operational relationship between the intermittent switch and relay contact of the conventional intermittent wiper device, and Figure 1 (C) is A principle diagram showing the operational relationship between the intermittent switch and the relay contact according to the present invention, Fig. 2 is a configuration diagram of a conventional circuit related to Fig. 1 (b), and Fig. 5 is a book related to Fig. 1 (C). A first embodiment of the relay contact protection circuit according to the invention, and FIG. 4 respectively show a second embodiment of the relay contact protection circuit according to the invention. In the figure, (Tr□~Tr, ) is a transistor, (M□
) is the wiper motor, (M*+ is the washer motor, (Lt) is the relay, (Dt~Do) is the diode, (
SW+) indicates all wiper motor interlocking cam switches. Patent applicant: Asmo Co., Ltd.

Claims (1)

[Claims] In a wiper device equipped with a circuit for controlling all operations of the wiper motor, detecting the contact position of a switch linked to the wiper motor, and detecting the contact position of the switch when the arm is connected to the side where the contact is not on the ground side. The wiper is equipped with a circuit that allows the relay contacts for wiper operation to be switched, so that even if an arc occurs when the contacts are switched, a short circuit is not formed and the contacts are not damaged. %,! : Relay contact protection circuit for wiper intermittent switch.